Real-Life Cases Show Some Types of 2FA Can Be Bypassed

Real-Life Cases Show Some Types of 2FA Can Be Bypassed

A number of cyber incidents in the past few years have demonstrated that certain types of multi-factor authentication or two-factor authentication (2FA) can easily be bypassed.

What Is Multi-Factor of Authentication? What Is 2FA?

Multi-factor authentication is an added layer of security in which a user is required to present two or more pieces of proof in order to be granted access to a computer system or application.

Two-factor authentication (2FA) is the more popular type of multi-factor authentication. In a typical 2FA, in addition to the traditional authentication method of a combination of username and password, a user is required to present one more authentication proof. Examples of these additional authentication proofs include a one-time code that changes over time, biometrics or behavioural information such as IP address, time of day or geolocation.

3 Ways 2FA Authentication Can Be Bypassed

In the past few years, the following 3 methods have been used to bypass or circumvent certain types of 2FA authentication:

1. Sim Swap

In bypassing 2FA using the SIM swap method, an attacker convinces a customer service representative of a phone company of an intended victim to do the SIM card swap to a SIM that the attacker controls, allowing the attacker to intercept the 2FA security codes intended for the victim to access a computer system or application.

Last month, the U.S. Federal Bureau of Investigation (FBI) issued an alert to its partner organizations warning them about SIM swapping. According to the FBI, between 2018 and 2019, SIM swapping is the most common tactic used by cyber criminals in circumventing the 2-factor authentication. Victims of SIM swapping attacks, the FBI said, had their bank accounts drained and their passwords and PINs changed.

Last year, Reddit disclosed that all Reddit data from 2007 and before including account credentials and email addresses as well as email digests sent by Reddit in June 2018 were illegally accessed. The company said that the weaknesses inherent to SMS-based 2FA appeared to be the root cause of this incident. The company added that “SMS-based authentication is not nearly as secure as we would hope, and the main attack was via SMS intercept”.

Reddit, however, didn’t specify how SMS-based 2FA one-time code was intercepted. At the time of the Reddit attack, the known methods in intercepting SMS-based 2FA one-time code were through SIM swapping and mobile number port-out scams.

In port-out scams, instead of a SIM swap, an attacker impersonates an intended victim and requests that the victim’s mobile number be transferred to another mobile network provider. In both SIM swap and port-out scams, one-time codes delivered by SMS are delivered to a phone controlled by the attackers.

2. Phishing Scheme

The second method by which 2FA can be bypassed is through phishing scheme. In December 2018, researchers at Certfa Lab detected a phishing campaign in which attackers, knowing that their victims use two-step verification in their Gmail and Yahoo accounts, created phishing pages for both desktop and mobile versions of Google and Yahoo mail services.

These phishing pages ask the victims their username and password combination, as well as 2-step verification code. The attackers then enter these username and password combination and 2-step verification code into Google or Yahoo’s genuine website and hijack the email accounts of their victims.

A victim is tricked into visiting one of these phishing sites by sending a fake email alert purportedly from the email provider, stating that unauthorized individuals have tried to access their accounts. This fake email alert asks the victim to review and restrict suspicious accesses via the link – leading to the attackers’ phishing site – provided in the email.

3. Session Hijacking

The third method by which 2FA can be bypassed is through session hijacking. Among the 3 methods of bypassing 2FA, session hijacking is more technical. 

A few months ago a toolkit that bypasses 2FA via session hijacking was publicly released. This toolkit uses Muraena and NecroBrowser. According to the authors of this toolkit, Muraena is a “custom target-agnostic reverse proxy solution”, while NecroBrowser takes care of the “instrumentation and session riding”. According to the FBI, Muraena tool intercepts traffic between a user and a target website which requires the usual username and password combination and 2FA code, while NecroBrowser allows cyber actors to hijack these private accounts and make changes to these accounts while maintaining access as long as possible.

Last month, security researchers at DEVCORE reported a different form of session hijacking that enabled them to access Twitter Intranet. According to the DEVCORE researchers, they were able to access Twitter Intranet by bypassing the 2FA of the SSL VPN used by the company.

“Twitter enabled the Roaming Session feature, which is used to enhances mobility and allows a session from multiple IP locations,” the DEVCORE researchers said. “Due to this ‘convenient’ feature, we can just download the session database and forge our cookies to log into their system!”

Preventive and Mitigating Measures

There’s a reason why multi-factor authentication or 2FA is widely used by organizations today. Instead of relying merely on the traditional username and password combination, multi-factor authentication provides an extra layer of security to systems or applications.

The use of multi-factor authentication can decrease numerous attack surfaces. Using multi-factor authentication, however, shouldn’t give your organization a false sense of security. As shown in the above-mentioned examples, certain types of multi-factor authentication or 2FA can be bypassed.